Yarn sizing process

ABSTRACT

A PROCESS FOR APPLYING A THIN SOLID ADHERENT POLYMERIC COATING TO AN ELONGATED FLEXIBLE STRUCTURE WHEREIN THE STRUCTURE WHILE MOVING AT HIGH SPEED TO A PACKAGING MEANS IS FIRST HEATED TO A TEMPERATURE BELOW ITS SOFTENING POINT AND THEN WHILE STILL HOT, COATED WITH AN UNHEATED LIQUID MIXTURE COMPRISING AN INERT, HIGH-BOILING SOLVENT AND AN ADHERENT POLYMERIC COATING MATERIAL. THE RELATIONSHIP OF SPEED, TEMPERATURE AND THICKNESS OF THE LIQUID MIXTURE APPLIED BEING SUCH TO ALLOW VAPORIZATION OF THE   SOLVENT AND DRYING OF THE POLYMERIC MATERIAL ON THE FLEXIBLE STRUCTURE BEFORE PACKAGING.

Dec. 7, 1971 G. A. FERNSTROM ETA!- YARN SIZING PROCESS Filed Oct. 31, 1968 INVENTORS A. FERNSTROM J. STROHMAIER w. WHITMAN BY ,g/

GEORGE ALFRED ROBERT ATTORNEY United States Patent Oflice 3,625,735 Patented Dec. 7, 1971 3,625,735 YARN SIZING PROCESS George A. Fernstrom, Alfred J. Strohmaier, and Robert W. Whitman, Seaford, Del., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del.

Filed Oct. 31, 1968, Ser. No. 772,080 Int. Cl. B44d 1/02; D06m 13/00; D06p 7/00 U.S. Cl. 117-47 A 6 Claims ABSTRACT OF THE DISCLOSURE A process for applying a thin solid adherent polymeric coating to an elongated flexible structure wherein the structure while moving at high speed to a packaging means is first heated to a temperature below its softening point and then while still hot, coated with an unheated liquid mixture comprising an inert, high-boiling solvent and an adherent polymeric coating material. The relationship of speed, temperature and thickness of the liquid mixture applied being such to allow vaporization of the solvent and drying of the polymeric material on the flexible structure before packaging.

This invention relates generally to a novel process for applying a thin polymeric coating to a flexible solid substrate. In one important specific aspect, the invention is concerned with a new method for preparing a sized textile yarn.

Thin polymeric coatings of many types are applied to flexible solid substrates for various purposes, and many procedures have been developed for accomplishing this result. In one commonly used procedure, the polymeric coating material is diluted with a carrier liquid, applied to the surface of the substrate, and then allowed to dry by vaporization of the liquid. Where a short drying time is desirable, the coated substrate is heated to raise the temperature of the material and thereby hasten the evaporation of the liquid.

Where the substrate to be coated is a thin flexible structure having a longitudinal axis of considerable length, such as ribbons, films, webs, sheets, fabrics, yarns and filaments, it is common practice to apply the coating mixture to the moving substrate as it is unwound from one roller and wound upon another roller. Obviously an adherent coating material will cause succeeding layers of the substrate to stick to each other unless the coating is properly dried before the final winding occurs. Hence, such a process must be run either at very slow speeds to allow time for air drying, or an adequate heating stage must be introduced after coating to vaporize the carrier liquid before the final windup.

A specific example of such coating processes is found in the preparation of sized yarns for Weaving. In the welknown slashing operation, for example, a group of parallel yarns are passed through an aqueous mixture containing a size and then the coated yarns are passed around heated cans which dry the yarns. Following drying, the yarns are wound up on a Warp beam. Because of the heat sensitivity of organic sizes, high can temperatures must be avoided and consequently speeds are low, usually less than 250 y.p.m. Various procedures and apparatus for accomplishing this process are known in the art. The process is slow, the equipment expensive, and a heavy coating of size is usually needed to provide satisfactory operation in weaving.

In continuous processes for drying an aqueous dispersion or solution on paper or film, drying temperatures are usually maintained below C. to prevent damage to the coatings. However, higher temperatures have been disclosed. For example, Hart in US. Pat. No. 2,919,205 has described a continuous process for coating paper in which the paper is coated with an aqueous mixture containing a mineral pigment and adhesive matter and the Wet paper placed under high pressure until the temperature has been raised above 100 C., whereupon the pressure is released and the water vaporized.

SUMMARY OF THE INVENTION The present invention provides a novel high-speed process for applying a thin, solid, adherent, polymeric coating to a flexible structure having a longitudinal axis. The invention provides for rapid drying of a liquid coating mixture while avoiding the complications of heating a wet, coated substrate. The invention further provides for the application of highly uniform coatings on thin flexible structures.

In its broadest concept, the present invention provides a process for applying a thin, solid, adherent polymeric coating to a flexible structure having a longitudinal axis wherein the structure, while moving at high speed, is first heated to a temperature below its softening point and then while still hot, coated with an unheated liquid mixture comprising an inert, high-boiling solvent and an adherent polymeric coating material. The important novel feature of the process is that the conditions are such that the heat content of the hot flexible structure is sufficient to vaporize the solvent and dry the coating on the flexible structure before that structure contacts another solid element such as a guide, roller, bobbin, or other winding core. No heating step is used after the coating is applied to the structure.

The structure may be composed of any suitable polymer having a melting point well above C. and having sufficient strength and pliability for high speed processing. Examples of suitable polymers include polyamides such as polyhexamethylene adipamide, polyesters such as polyethylene terephthalate, acrylic polymers such as polyacrylonitrile, polymers derived from cellulose such as viscose rayon, and many others.

The expression solid, adherent, polymeric coating is intended to include coating materials which are normally solid at room temperature, which have a natural aflinity for the substrate so that they form a tightly held surface layer, and which are polymeric in character, either natural or synthetic.

It is essential that the temperature of the moving structure to be coated, as it enters the coating zone, be at least 80 C. Temperatures above the softening temperature of the structure are usually avoided. The optimum temperature of the structure, for best coating results, will depend upon the amount of coating to be applied, the proportion of solids to vaporizable liquid in the coating mixture, the heat of vaporization of the liquid, and the speed of operation.

The process is preferably operated at high speeds. Speeds of several hundred yards per minute are recommended and speeds of several thousand yards per minute are preferred for light stuctures such as yarns.

Because of the high speed of the process, the coating materials are exposed to an elevated temperature for only a very short time, usually less than 0.05 second. Consequently coating materials which are sensitive to elevated temperatures can be used in the process of this invention, whereas their use in a process of the prior art requiring longer drying times at high temperatures would be precluded.

In the process of the invention, the coating mixture may be applied to the thin flexible structure by a wide variety of suitable methods, such as, contacting the structure with a wetted applicator roller, passing the structure through a slot applicator, using a doctor knife or doctor roll, or spraying the liquid mixture on the structure. However, procedures will be avoided in which the structure to be coated traverses a considerable distance underneath the surface of the cold coating mixture since excessive. heat loss from the structure is encountered in such procedures.

Any suitable means may be used to heat the thin flexible structure to the desired temperature. The structure may be passed around heated rolls, over a stationary heated surface, through a hot liquid, or through a hot gas zone. Alternatively, heating may be obtained by infrared radiation, by microwave radiation or by laser beam.

It will be recognized that the process becomes inoperable if a very heavy load of coating mixture is applied to a light weight structure. Preferably, the layer of coating mixture applied has a thickness no greater than about one fifth the thickness of the structure to be coated.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic illustration of an apparatus arrangement used in practicing the preferred process of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, yarn 1 advancing from a source not shown, is passed around heated rolls 2 and 3 enclosed in box enclosure 4. The yarn makes a number of wraps around the rolls to assure that the yarn temperature approaches that of the rolls. The heated yarn then leaves enclosure 4, and While still hot contacts rotating applicator roll 5 which is immersed in an unheated liquid mixture contained in pan 6. The wetted yarn which is almost instantaneously dried next passes through guide 7 and then proceeds to a surface-driven package 8 driven by roll 9.

The invention will be discussed with specific reference to the preparation of a sized yarn because of the highly desirable results obtained in this area. Furthermore because of the many advantages of the use of water as a diluent or solvent, e.g. low toxicity, non-flammability, low cost and ready availability, the examples illustrating the invention show only the use of aqueous coating mixtures.

In the weaving and knitting arts it is customary to size yarns prior to the weaving and knitting process in order to impart greater cohesiveness, compactness, smoothness, increased strength and improved resistance to abrasion. To obtain these effects, the sizing material must form a film that adheres to the yarn, that is sufiiciently lubricating to permit the yarn to slide over the various surfaces that come in contact with it, that is elastic and flexible and preferably forms a film that is transparent. Furthermore, in most instances, the sizing material should be readily removable by normal methods of de-sim'ng.

The sizing of yarns and filaments consists of the coating or impregnation of said yarns or filaments with a suitable sizing agent which may be in the form of either a lacquer or an aqueous solution or dispersion. Aqueous dispersions of starch and starch derivatives have historically been used to size cotton and other natural fibers. Starchbased dispersions, however, have not been applicable to the sizing of synthetic fibers and filaments because of stability and viscosity variations of their dispersions and their rather limited affinity for the synthetic materials. Practitioners of the weaving and knitting arts now use polymeric materials such as polyvinylalcohol, polyacrylic acid, polymeth'acrylic acid, and the like, as sizing agents for synthetic fibers and filments. A Wide variety of sizing agents are known for use as knitting and weaving sizes. Any of the known sizes when used with the fiber for which they are normally considered suitable may be used in the present invention.

Yarns sized by the process of this invention may be composed of natural fibers such as cotton and wool, or synthetic filaments such as the polyesters or polyacrylics, or mixtures of these. As illustrated in the example, the process is particularly suitable for the sizing of polycarbonamide yarns.

A particularly advantageous and surprising feature of this sizing process is that it can be operated at speeds well above 500 yds./min., whereas prior art processes have generally been low speed process. As a matter of fact, the process of the present invention appears to be aided by the use of high speeds. The air turbulence immediately surrounding the yarn traveling at high speeds appears to aid the evaporation and removal of the water in the finish mixture. The process of the invention has been operated at speeds of 3,000 and 3,500 yds./min. with highly satisfactory results. No upper speed limitation is apparent except that imposed by the limitation of available equipment.

The preparation of sized yarns by the process of the present invention provides for a saving in sizing material. It has been found that with this process, much lighter coatings of size are needed to provide equivalent sized yarn performance. For example, whereas prior processes might require from three to five percent size loadings on yarn, the present invention provides equivalent results with loadings of 0.1 to 1.2% of size.

The high speeds afforded by the process of the present invention allow the process to be inserted in existing highspeed textile manufacturing or processing procedures so that a separate sizing step, and equipment for it, becomes unnecessary. For example, the present process may be inserted in an existing synthetic yarn manufacturing process where yarn is passed around a heated roller for dimensional stabilization before being Wound up. In this instance the only added equipment needed is a liquid applicator located immediately downstream from the hot roll.

It is appreciated that liquid finishes have been applied to moving yarns in a variety of ways, including application immediately downstream from a heated roller. However, no disclosure is known of the application of a size or other adherent solid polymeric material to a hot yarn with a recognition of the fact that the relationship of latent heat in the yarn and yarn speed could be suflicient to evaporate the aqueous carrier and provide a dried coating in an extremely short time.

In an important embodiment of the invention, the sizing mixture used to provide sized yarns also contains materials acting as lubricants, plasticizers, emulsifiers and antistatic agents. It will be appreciated that a more uniform ratio of size to other ingredients of the mixture, along the end of the coated yarn, can be obtained by applying all ingredients from a single mixture. Separate application of such different materials, as in conventional sizing or even in the use of tandem applicator rolls in a continuous process, usually results in non-uniform ratios of the materials along the end of the yarn.

In the examples, the notation APDC refers to a measurement of filament entanglement, or degree of interlacing, in a multifilament yarn. APDC is measured automatically by the apparatus of Hitt, described in US. Pat. No. 3,290,932. The apparatus measures the length of yarn, in centimeters, which can be passed thorugh a test point before entangled or intermingled filaments deflect a needle projecting transversely through the moving yarn bundle. This length of yarn, usually an average of l0 determinations, is reported as the automatic pin drop count, or APDC number (in centimeters). For the re-' sults reported in the examples, the tension device is set to provide a tension of gms. in the test yarn, and the yarn passed through the apparatus at a speed of 100 inches/min. The apparatus is adjusted so that a force of 4 or 8 gms. is required to trip the needle probe as noted for each test value.

The term zero-twist yarn as used herein refers to a yarn which has no measurable twist in several yards of length.

The term multifilament yarn as used herein refers to a textile denier yarn having at least five filaments in the yarn bundle. The yarn may contain as many as 200 filaments or more in the bundle, but most common textile denier yarns contain fewer than 100 filaments.

In the examples, yarn tenacity and break elongation are measured on an Instron tensile tester using a constant rate of elongation of 10% /min. and a sample length of 10 inches.

The concentration of polyacrylic acid on yarn is measured by immersing a weighed sample in 100 mls. distilled water and heating slowly to 80-85 C. over a period of 60 minutes, cooling, and then titrating the solution, in the presence of the sample, with 0.1 N NaOH using phenolphthalein as an indicator. The end point is sharpened by adding 2 grams of NaCl after a faint pink color is obtained, and then continuing the titration to a definite pink color. Results are calculated from the equation.

ml. NaOH X NormalityX 7.2

We1ght Percent PAA= Weight of Sample The concentration of finish oils on yarn is determined by extracting the oils from a weighed sample with carbon tetrachloride, evaporating the carbon tetrachloride, and weighing the residue.

In the examples, parts and percentages are by weight unless otherwise indicated.

Example I Ingredients: Parts Butyl stearate 70.2 Polyoxyethylene sorbitol hexaoleate 4.0 Fatty acid esthers of higher polyglycols 8.3 Oleic acid 2.3 Long chain alkyl phosphate 7.5 Potassium hydroxide 1.7

The first five ingredients in the table are heated on a hot plate up to 45 C. until all of the long chain alkyl phosphate has dissolved. Then the mixture is cooled to room temperature with stirring and the potassium hydroxide added as a. 45% solution in water. This mixture is then diluted with distilled water to provide a 12% emulsion. 400 parts of the emulsion is then stirred while 126 parts of a 25% aqueous solution of polyacrylic acid is slowly added. The final mixture contains 6% polyacrylic acid.

Polyhexamethylene adipamide is melt-spun through a 34 hole spinneret, quenched in cross-flow air, and passed over a primary finish roll where an antistatic aqueous finish is applied. The active ingredient of the finish is polyethylene glycol-di-2-ethylhexoate. The yarn is then wrapped 2 /2 times around an unheated feed roll and accompanying separator roll operating at 876 yds./min., from which it proceeds to the first draw roll (unheated) which is operated at 2,283 yds./min. The yarn makes 3 /2 wraps around the first draw roll, with its accompanying separator roll, and then proceeds to a pair of secondary draw rolls operating at 3,114 yds./min. and heated to a temperature of 190 C. 17 /2 wraps are made around the pair of hot-draw rolls and then the heated yarn proceeds to a size applicator roll, spaced 10% inches from the hot-draw roll, where the above described sizing mixture is applied at room temperature by momentary tangential contact. The temperature of the yarn 8 /2 inches above the size roll is about 170 C., as measured by an infra-red temperature meter. The size roll has a diameter of 4 inches and rotates in the direction of yarn travel at a speed of 14 r.p.m. Leaving the sizing roll, the yarn travels 2 /2 inches before it encounters the next guide surface and then the yarn proceeds to a surface driven bobbin windup, located 40 inches from the sizing roll, which is operated at a speed of 2,950 yds./min. The yarn is quite dry before it reaches the bobbin.

The above process is operated for a period of several weeks to produce several hundred six-pound packages of sized yarn. Examination of the product reveals that it is a flexible zero-twist, non-interlaced (APDC value: cm. using 8 gms. tripping force), sized nylon yarn having an average denier of 70.4, a tenacity of 5.4 g.p.d., a break elongation of 37.4%, an initial modulus of 27.9 g.p.d., and a boil-off shrinkage of .0%. The average loading of size on yarn is 0.234% by weight, with a remarkable degree of along-end uniformity. Finish oils are present at a level of 0.634% by weight. The yarn has a surprising degree of cohesion for the relatively small amount of size applied.

(Conventional slasher sizing usually results in size-onyarn loadings of 25% It is found that the size is easily and quickly removed from the yarn by immersing the sized yarn in cold water. This characteristic is in contrast to that of sized yarns produced by conventional slashing processes which usually require a hot alkaline scour for size removal.

The yarn prepared above is quilled and woven as filling in a taffeta fabric using a quilling tension of 18 gms. and a shuttle tension of 10 gms. Loom settings are adjusted to give 68 picks per inch. The warp for this fabric was prepared from.a commercial 7034 66 nylon yarn twisted and slasher-sized in the customary manner.

For comparison, sections of filling yarn are inserted in the same warp from a high-quality, commerciallyavailable 7034 zero-twist, interlaced 66 nylon yarn having an APDC count of 16 cm. (measured with a tripping force of 4 gms.).

After completion of weaving, the fabric is divided into two sections and one section dyed gray with acid dyes and a second section dyed red with premetalized dyes. Examination of the dyed fabric samples reveals that those portions containing the test yarn of this example are much superior in uniformity of appearance to the portions containing the commercially available filling yarns. Rated visually for filling uniformity on a 1 to 5 scale, where 1 is poor and 5 is excellent, the gray fabric prepared from the test yarn is given a rating of 3.7 vs. a rating of 1.5 for the commercial filling yarn. In the red fabric, the test yarn is rated 3.4 vs. a rating of 2.0 for the commercial yarn.

Example II This example illustrates the use of the process of the present invention in the preparation of a sized yarn suitable for use as a Warp yarn in woven fabrics.

The apparatus used is similar to that used in Example I with the exception that an interlacing jet of the type described in US. Patent 3,115,691, FIGS. 1, 3 and 4, is added so that yarn passing from the hot draw rolls 2 and 3 to the size applicator roll 5 must pass through the interlacing jet before it reaches roll 5. In operation, air pressure to the jet is p.s.i.g. Yarn roll speeds, temperatures, and the number of wraps around each roll are the same as in Example I. Size applicator roll 5 has a shallow circumferential groove at the line of contact with the yarn to supply a heavier size pickup to the moving yarn than was provided in Example I.

The size-finish mixture applied to the yarn by applicator roll 5 is the same as that shown in Example I except that the concentration is adjusted to 10%. Roll 5 speed is 16 r.p.m. in the direction of travel of the yarn.

Using the procedure and apparatus outlined above, a 34-filament polyhexamethyleneadipamide yarn is melt spun, quenched, drawn, interlaced, sized, and wound up on a surface-driven package using a windup speed of 2,982 yds./min. The sized yarn is completely dry before it reaches the windup. The zero-twist yarn on the package is examined and found to have a total denier of 70.6, a tenacity of 5.1 g.p.d., a break elongation of 33.9%, an initial modulus of 26.9 g.p.d., and a boil-off shrinkage of 5.4%. The yarn can be unwound from the package without noticeable sticking or plucking. Analysis for size gives a value of 1.27% polyacrylic acid based on weight of fiber. Analysis of finish gives a value of 1.22% finish oils based on weight of fiber. Examination of the degree of interlace using the APDC test gives a value of 4.5 cm. (8 gms. tripping force). The yarn shows good cohesion, low friction, and excellent along-end uniformity of size-to-finish-oil ratio. The uniformity of along-end yarn modulus and flexibility is also quite remarkable.

Immersion of a sample of the yarn in cold water results in immediate solution and removal of the size from the yarn.

The above-sized yarn is made into a fabric warp, without further sizing or twisting, by first transferring the yarn from the windup packages to a silk mill and then backwinding from the silk mill to a loom beam. The warp is then used to prepare a taffeta fabric on a standard loom using a sley count of 96 ends per inch and a pick count of 68 ends per inch. Excellent processability is observed. 150 yds. of fabric is woven without a break.

The fabric is scoured and dyed gray as described in Example I and found to show a remarkable degree of warp-direction uniformity.

For comparison, an interlaced yarn is prepared according to the above procedure without the presence of polyacrylic acid in the solution applied from finish roll 5. This yarn is made into a warp, without sizing or twisting, and an attempt made to weave a taffeta fabric. Yarn breaks prevented weaving.

In those embodiments of the invention, as illustrated in the examples, where it is desirable to apply a size in combination with finish oils, much superior results will be obtained if the ratio of size-to-oil is such that enough oil is present to exceed the normal, maximum solubility level of oil in size. With this preferred ratio, the oil forms a separate protective layer on the outside of the size film and provides a further reduction in yarn friction, with an attendant increase in processability. Where the size is polyacrylic acid and the oil is a mineral oil, a size/ oil ratio in the range 0.4 to 1.0 to 100% by weight) is preferred. Where the oil is an ester of a long chain fatty acid, a size/oil ratio in the range 0.3 to 0.9 (30 to 90% 'by weight) is preferred.

It will be apparent to those skilled in the art that the invention described herein is applicable to many types of synthetic fibers including those having non-round crosssections such as trilobal, hexalobal or cruciform; filaments containing either discontinuous or continuous longitudinal voids; filaments containing dispersed pigments of various types including those described in U.S. Patent 3,397,171; filaments formed from melt blends of dissimilar polymers such as those described in British Patents 918,637 and 963,320; mixed filaments of different polymers spun simultaneously from different holes of the same spinneret, e.g. 66 nylon cospun with a copolymer of adipic acid, isophthalic acid and hexamethylenediamine; composite filaments made up of two distinct polymeric components such as those described in British Patent 805,003; and many other variations.

As indicated elsewhere, the invention finds its greatest utility in the preparation of sized yarns from synthetic linear polycarbonamide filaments. The term synthetic linear polycarbonamide is intended to include any linear polymer having recurring units of the formula as integral parts of the main polymer chain, wherein R is hydrogen or a monovalent hydrocarbon radical, the average number of carbon atoms separating the amide groups being at least two, said polycarbonamide having an intrinsic viscosity of at least about 0.4, as defined in U.S. Patent 2,130,948. Particular polycarbonamides included among those which are useful in'this invention are as follows: polyhexamethylene adipamide, polyhexamethylene sebacamide, polymerized 6-amino-caproic acid, polytetramethylene sebacamide, polytetramethylene adipamide, polymetaxlylene adipamide, the polyamide from bis(4-aminocyclohexyl)methane and azelaic acid, sebacic acid, decamethylene-l,IO-dicarboxylic acid or dodecane- 1,12-dioc acid, and the polyamide from Z-methylhexamethylene diamine and terephthalic acid. The invention is also applicable to other polymers and various copolymers, either block or random, such as the copolymer of polyhexamethylene adipamide and polyhexamethylene isophthalamide and the copolymer of polyhexamethylene adipamide, and polyhexamethylene-t-butyl isophthalamide. Other suitable polycarbonamides are disclosed in U.S. Patent Nos. 2,071,251 and 2,071,253.

What is claimed is:

1. A process for sizing yarn comprising:

(a) advancing the yarn from a source through a heating zone at a speed greater than 500 yards per minute;

(b) heaitng the yarn to a temperature of at least about C. but below the melting point of the yarn; and

(c) the final step before winding into a package of applying a coating of an unheated aqueous size mixture to the advancing heated yarn, said coating having a thickness less than about one fifth the thickness of the yarn, the relationship of the speed, temperature and coating thickness of the yarn being sufficient to dry the size coating on the yarn before winding.

2. The process as defined in claim 1, said yarn comprising polycarbonamide filaments.

3. The process as defined in claim 2, wherein said aqueous size mixture comprises polyacrylic acid.

4. A process for applying a coating to synthetic linear polycarbonamide filaments comprising:

(a) advancing the filaments from a source through a heating zone at a speed of about 3000 yards per minute;

(b) heating the filaments to a temperature of about (c) applying a coating of an unheated liquid mixture comprising water and polyacrylic acid to the ad vancing heated filaments, said coating having a thickness less than about one fifth the thickness of the filaments; and

(d) immediately winding the filaments into a package, the relationship of the speed, temperature and coating thickness of the filaments being sufficient to vaporize the water and dry the polyacrylic acid on the filaments before winding.

5. The process as defined in claim 4 said polyacrylic acid being about 6% by weight of said mixture said fila- 9 merits bearing from about 0.1 to about 1.3% by weight of said polyacrylic acid after drying.

including a finish oil the ratio of polyacrylic acid to finish oil in said mixture being in the range of from about 30 to about 100% by weight.

UNITED 10 2,919,205 12/1959 Hart. 2,306,401 12/1942 Miles. 16. The process as defined in claim 4-, said mixture 3,281,223 10/1966 Simison 1l7119.6 3,143,405 8/1964 Wong 2875 5 3,511,677 5/1970 Strohmaier et a1. 2875 FOREIGN PATENTS References Cited 1,002,570 8/ 1965 Great Britain. STATES PATENTS 1,011,662 12/1965 Great Britain. Brodie 11747 X 10 WILLIAM D. MARTIN, Primary Examiner learn 117-47 X Cohn 117 47 W. R. TRENOR, Assistant Examiner Campbell 11747 Loomer 117 111 X Kuhn 117 111 X 15 11766,105.3,138.8,139.5,140,47A Newman 11747 X 

